I don't think it is a triggerfish...Facial markings look like a Maori Wrasse (or Humphead wrasse/napoleon wrasse/napoleon maori wrasse - or any combination of these )I can't see a prominent hump and this looks a lot smaller than the typical adult maori wrasse... perhaps a juvenile one? Or I could be completely wrong and it may be a triggerfish - I haven't looked at fish ID books in a while.

I don't think it is a triggerfish...Facial markings look like a Maori Wrasse (or Humphead wrasse/napoleon wrasse/napoleon maori wrasse - or any combination of these )I can't see a prominent hump and this looks a lot smaller than the typical adult maori wrasse... perhaps a juvenile one? Or I could be completely wrong and it may be a triggerfish - I haven't looked at fish ID books in a while.

Where did you see the fish? (And very nice photo by the way)

Yep. That's definitely a juvenile. They tend to get a bit greener and the bump becomes more prominent as they get older. I've spent many dives feeding one in the local aquarium.